CLP are major producers of M-pDCs and CMP produce mainly M-cDCs. Within control M-CSF cultures containing only UBC-GFP BM cells, all cells expressed high levels of GFP and fluoresced strongly in the FITC (GFP) channel (A left panel). The progeny of C57BL/6 progenitors spiked into UBC-GFP BM cultures were gated as FITC/GFP^neg cells (A right panel). Serial dilutions of CLP, CMP, or GMP (625 to 39 cell equivalents are shown) were added to 1.0 × 10⁶ UBC-GFP BM cells in 1 mL, and M-CSF cultures were carried out for 6 days. GFP^negPI^neg cells were gated and stained with CD45RA and CD11c. The resulting M-DC plots are shown in panel B, and the gates used to determine M-pDCs and M-cDCs are shown in the top left contour. The absolute number of M-pDCs and M-cDCs obtained in the cultures of panel B are shown in panel C. Data shown are from one experiment. Similar results were obtained in a second experiment. (D) The expression of CD115 (M-CSFR) and CD135 (Flt3) on CLP is shown. Gray histogram represents CLP stained with a PE-conjugated isotype control. Staining was carried out in 2 individual experiments (CD115) with similar results, and one of these experiments also included the CD135 staining.